occurs when the two surfaces in contact are not in motionvaries in strength from zero to some maximum value static force - the force that overcomes the static frictionEX: A person walking on the ground.occurs when two surfaces in contact are in relative motionacts on objects when they are sliding over a surface. is weaker than static frictionkinetic force - the force required to maintain steady slidingEX: pencil lead on paperthe resistive force experienced by rolling objectsoccurs between solid surfacesacts on objects that are rolling on a surfaceis weaker than sliding or static friction.EX: Any type of wheel that is used to carry or transport an objectthe resistive force between surfaces in relative motion through a fluid the faster or larger a moving object is, the greater is the fluid friction resisting its motionEX: a swimmer's streamline, a skydiver' parachute

Factors Affecting FrictionTypes of material in contactForceCoefficient of Frictiondescribes the ratio of the force of friction between two bodies and the force pressing them togetherunit-lessa number usually between 0 – 1, the higher the number, the stronger the frictionthe coefficient is unique to every pair of objects

Factors That Don't Affect Frictionfriction is independent of:surface roughnessspeed once an object is movingmass and/or surface areaMaterialsProcedureData CollectedPicturesShoe Sole Composition1. Take one of the shoes and attach it to the spring scale via the hook.2. While still keeping the shoe attached to the spring scale, drag the shoe across the hallway floor. This floor must be the same floor to keep your results as accurate as possible.3. Read the measurement given by the spring scale just before the shoe starts to slide and record it on the data table in Newtons.4. Repeat steps 1-3 until all of the spaces on the data table have been filled up.

Spring ScaleDifferent types of shoes:-Rubber soled-Leather soled-Shoe with Paper attached to the bottom-Shoe with carpet attached to the bottom-Shoe with a Tissue attached to the bottomRubber SoledShoe with Paper Attached to the bottomShoe with a Tissue attached to the bottom1 Spring Scale1 Nike Shoe1 Constant Surface Type (polished concrete hallway floor)8 weights- .5 N (2)- 1.5 N (2)- 1 N (3)- 3 N (1)1. Hook the hook of the spring scale onto the front lace of the shoe.2. Set the shoe and the spring scale in one straight line.3. Gather the correct weights so that the combined total of the weights is 1 N.4. Place the weights in the heel of the shoe so that all the weights can be seen.5. Have one person slowly drag the shoe across the floor in a constant speed.6. Another group member should watch the spring scale.7. When the spring scale is steady, record that number in the data table.8. Repeat steps 5-7 twice more.9. Repeat steps 3-8 for the combined weights of 2, 3, 4, 5, 6, 7, 8, 9, and 10 N.1. Hook the hook of the spring scale onto the front lace of the shoe. 2. Set the shoe and the spring scale in one straight line.3. Place the weight (3 N) right on the heel of the shoe.4. Place this whole setting on the hallway floor (polished concrete).5. Pull the shoe by the spring scale at a constant speed. 6. Record the number on the spring scale on the data table.7. Repeat steps 4 – 6 twice more.8. Repeat steps 1 – 7 for the other test surfaces

Shoe with 3 N ConcreteGrassHallwayThanks for Listening!Presentation by:Miranda Li, Sean Rossander, and Reilly LarceyAsphaltShoe Sole Materials• In general different types of shoes contain:- Rubber- Plastic- Leather- Carpet (made for sliding)• Rubber soles are easily made and provide good traction • Leather soles do not provide very much traction

Shoe Patterns• adds and subtracts surface area between the shoe and the floor. • The texture of the pattern - slides or grips different surfaces.• the textures of the shoe and the shoe sole pattern will grip any cavity in the ground and give the wearer more traction.